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Induction Motor Brake

IP.com Disclosure Number: IPCOM000091230D
Original Publication Date: 1969-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Cuzner, DE: AUTHOR [+4]

Abstract

Induction motor 1 has main winding L1 and start winding L2, the latter being connected through start capacitor 2 for energization in parallel with winding L1 from an AC supply upon operation of start switch 3. The latter has a stop position arranged to connect the AC supply through diode 4 and the contacts of relay R1 to winding L2. Relay R1 is energized through a transistor drive circuit when the rotor speed drops below a predetermined limit, for example, 30 rpm, at which point the contacts of R1 open. Thus, when switch 3 is moved to the stop position, winding L2 of motor 1 receives an energization having a DC component. This provides a steady retarding torque and an AC component which produces a counterrotating magnetic field which also provides a retarding torque.

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Induction Motor Brake

Induction motor 1 has main winding L1 and start winding L2, the latter being connected through start capacitor 2 for energization in parallel with winding L1 from an AC supply upon operation of start switch 3. The latter has a stop position arranged to connect the AC supply through diode 4 and the contacts of relay R1 to winding L2. Relay R1 is energized through a transistor drive circuit when the rotor speed drops below a predetermined limit, for example, 30 rpm, at which point the contacts of R1 open. Thus, when switch 3 is moved to the stop position, winding L2 of motor 1 receives an energization having a DC component. This provides a steady retarding torque and an AC component which produces a counterrotating magnetic field which also provides a retarding torque. When the rotor speed drops below the predetermined limit, contacts R1 open, preventing the slight reverse creepage which otherwise occurs after motor 1 comes to rest due to the alternating component of the energization of L2.

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